Sheet post-processing apparatus

ABSTRACT

A sheet post-processing apparatus includes a saddle tray on which are stacked bundles of sheets having undergone center folding processing and a movable tray that ascends and descends while sheets having undergone post-processing other than center folding are stacked thereon. The saddle tray is coupled to the movable tray and a mechanism to allow the saddle tray to ascend and descend in association with the movable tray is provided. The movable tray is driven to a lower position before the bundles of sheets are discharged for the bundles of sheets to be stacked on the saddle tray. After the bundles of sheets are discharged, the movable tray is driven to an upper position for the stacking portion of the saddle tray to standby at a high position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet post-processing apparatus that performs post-processing on sheets discharged from an image forming apparatus, such as a copying machine and a printer.

2. Description of the Related Art

Recently, there has been extensively used a sheet post-processing apparatus that takes in sheets discharged from an image forming apparatus, such as a copying machine and a printer, to perform alignment processing, saddle stitching processing, punching processing, sorting processing, center folding processing and the like (for example, JP-A-2006-151598).

In a typical sheet post-processing apparatus as described above, however, bundles of sheets having undergone the saddle stitching processing and the center folding processing (hereinafter, referred to as booklet making processing) are stacked on a saddle tray fixed at a lower position of the apparatus, which poses a problem that it is difficult for the user to take out the bundles of sheets stacked on the saddle tray. In addition, a movable tray on which are stacked sheets having undergone post-processing other than the booklet making processing is of a structure designed by placing great importance on ease of operation when the booklet making processing is not performed, and is not suitable to stack bundles of sheets having undergone the booklet making processing. Further, additionally providing an elevation driving mechanism for the saddle tray poses a problem because it results in an increase of the manufacturing costs of the sheet post-processing apparatus and an increase of the apparatus in size.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a sheet post-processing apparatus provided with a saddle tray coupled to a movable tray.

In an aspect of the present invention, a sheet post-processing apparatus includes: a movable tray allowed to ascend and descend and configured to stack thereon sheets having undergone post-processing; discharge means for discharging bundles of sheets having undergone center folding processing; and a saddle tray provided at a lower position from the movable tray and configured to stack thereon the bundles of sheets discharged via the discharge means, wherein the saddle tray is coupled to the movable tray.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view used to describe the overall configuration of a sheet post-processing apparatus according to one embodiment of the present invention;

FIG. 2 is a view used to describe a state where a saddle tray of the sheet post-processing apparatus according to one embodiment of the present invention has ascended together with a movable tray;

FIG. 3 is a perspective view used to describe the structures of the saddle tray and an arm member; and

FIG. 4 is a cross section used to describe the structures of the saddle tray and the arm member.

DETAILED DESCRIPTION OF THE INVENTION

Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus and methods of the present invention.

Hereinafter, one embodiment of a sheet post-processing apparatus 1 of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view used to describe the overall configuration of the sheet post-processing apparatus 1 of this embodiment.

The sheet post-processing apparatus 1 takes in sheets on which are formed images by the image forming apparatus to perform desired post-processing thereon. The post-processing includes, for example, alignment processing to align plural sheets that have been taken in, end stitching processing to wire-stitch a bundle of sheets at one end, saddle stitching processing to wire-stitch a bundle of sheets at the center, punching processing to punch out a hole (or holes) at one end of sheets that have been taken in, sorting processing to sort sheets, center folding processing to fold sheets at the center, and so forth, which can be chosen by the user. Accordingly, paper discharge ports are switched for the sheets having undergone the post-processing according to the content of the post-processing for the sheets to be stacked on the tray corresponding to the paper discharge port.

The sheet post-processing apparatus 1 includes a first paper discharge port 2, a second paper discharge port 3, a movable tray 4, a saddle tray 5, and an arm member 6.

The first paper discharge port 2 is a sheet discharge port provided at an upper position in the side surface of the sheet post-processing apparatus 1. From the first paper discharge port 2, sheets having undergone, for example, the alignment processing, the punching processing, and the sorting processing are discharged using an internal paper discharge roller (not shown).

The second paper discharge port 3 is a paper discharge port provided at a lower position from the first paper discharge port 2. From the second paper discharge port 3, bundles of sheets having undergone the booklet making processing, such as the saddle stitching processing or the center folding processing, are discharged using an internal paper discharge roller (not shown).

The movable tray 4 is allowed to move in a vertical direction by an internal elevation driving mechanism (not shown) along the side surface of the sheet post-processing apparatus 1 in which the first paper discharge port 2 and the second paper discharge port 3 are provided, and it is a tray on which sheets discharged from the first paper discharge port 2 are stacked. The saddle tray 5 and the arm member 6 are fixed to the movable tray 4 at a lower position on the backside of the sheet stacking surface using a coupling member (not shown) to form a single piece. The interval between the movable tray 4 and the saddle tray 5 is set so that the saddle tray 5 is present at a lower position from the second paper discharge port 3 when the movable tray 4 has descended in close proximity to the lowermost portion.

The saddle tray 5 moves in association with the ascending and the descending of the movable tray 4 to which it is coupled, and it is a tray on which bundles of sheets having undergone the booklet making processing and discharged from the second paper discharge port 3 are stacked. The saddle tray 5 is preferably strong enough to stack, for example, at least 150 sheets or so. The size of the saddle tray 5 corresponds to the largest length of a sheet handled by the sheet post-processing apparatus 1.

The arm member 6 is provided between the movable tray 4 and the saddle tray 5, and receives bundles of sheets having undergone the booklet making processing and discharged swiftly from the second paper discharge port 3, so that the bundles of sheets are stacked on the saddle tray 5 in a stable manner. The bundles of sheets therefore will never jump out from the saddle tray 5.

A relation between the ascending and the descending of the movable tray 4 and the booklet making processing will now be described.

In a case where the booklet making processing is performed, as is shown in FIG. 1, the movable tray 4 descends to a position at which bundles of sheets discharged from the second paper discharge port 3 can be stacked on the saddle tray 5. When the booklet making processing is performed and the stacking of the bundles of sheets completes, the movable tray 4 ascends near the first paper discharge port 2 together with the saddle tray 5. FIG. 2 is a view showing a state where the movable tray 4 has ascended together with the saddle tray 5.

Referring to FIG. 3 and FIG. 4, a detailed description will be given for the saddle tray 5 on which the bundles of sheets having undergone the booklet making processing are stacked and the arm member 6 that presses the top surface of the bundles of sheets.

FIG. 3 is a perspective view used to describe the structures of the saddle tray 5 and the arm member 6. FIG. 4 is a cross section of FIG. 3. The direction of a linear arrow indicates the transportation direction of sheets.

The saddle tray 5 is formed of a sheet stacking unit 5 a and a stopper 5 b. The sheet stacking unit 5 a is inclined downward on the downstream end in the transportation direction of the bundles of sheets, so that the bundles of sheets discharged successively from the second paper discharge port 3 slide down toward the stopper 5 b. The stopper 5 b is formed almost perpendicularly on the sheet stacking unit 5 a at the tip end portion on the downstream end in the transportation direction. The stopper 5 b has a plane that prevents bundles of sheets from falling off from the sheet stacking unit 5 a and aligns the bundles of sheets as they hit against it. It is thus possible to suppress an abrupt jumping out of a bundle of sheets, which makes it possible to stack the bundles of sheets in a stable manner.

The arm member 6 is formed of a pressurizing arm 6 a, an arm oscillation supporting point 6 b, a guide arm 6 c, and a guide roller 6 d. The pressurizing arm 6 a is the main body of the arm member 6, and oscillates about the arm oscillation supporting point 6 b provided in close proximity to the second paper discharge port 3 as the supporting point. The guide arm 6 c that oscillates about the arm oscillation supporting point 6 b as the supporting point is connected to the pressurizing arm 6 a on the second paper discharge port 3 side. When the bundles of sheets are discharged from paper discharge rollers 3 a through 3 c inside the second paper discharge port 3, the bundles of sheets first come into contact with the guide arm 6 c and a force in the transportation direction is absorbed. As a consequence, the bundles of sheets are guided in the direction of the paper stacking unit 5 a of the saddle tray 5 and stacked on the sheet stacking unit 5 a. As the number of the bundles of sheets on the sheet stacking unit 5 a increases, the bundles of sheets start to come into contact with the guide roller 6 d provided at the tip end of the pressurizing arm 6 a. The bundles of sheets then slide into a lower position due to oscillations of the arm member 6 and rotations of the guide roller 6 d, and the top surface of the bundles of sheets is pressed in the direction of the sheet stacking unit 5 a by the arm member 6. The length or the range of oscillation of the arm member 6 may be changed, so that it is configured in such a manner that the bundles of sheets are pressed from the top surface regardless of the number of stacked bundles of sheets.

By configuring as described above, the saddle tray 5 ascends to a height at which the user readily takes out the bundles of sheets, which contributes to an enhancement of the work efficiency of the user. In addition, because there is no need to provide a new driving mechanism to ascend and descend the saddle tray 5, the development can be achieved at a low cost while avoiding an increase of the sheet post-processing apparatus in size. Further, by attaching the arm member 6, it is possible to prevent a bundle of sheets folded at the center insufficiently from opening at one end, which makes it possible to stack the sheets on the saddle tray 5 in a stable manner.

Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the sprit of the present invention. All such changes, modifications, and alterations should therefore be seen as within the scope of the present invention. 

1. A sheet post-processing apparatus, comprising: a movable tray allowed to ascend and descend and configured to stack thereon sheets having undergone post-processing; discharge means for discharging bundles of sheets having undergone center folding processing; and a saddle tray provided at a lower position from the movable tray and configured to stack thereon the bundles of sheets discharged via the discharge means, wherein the saddle tray is coupled to the movable tray.
 2. A sheet post-processing apparatus, comprising: a movable tray allowed to ascend and descend and configured to stack thereon sheets having undergone post-processing; discharge means for discharging bundles of sheets having undergone center folding processing; a saddle tray provided at a lower position from the movable tray and configured to stack thereon the bundles of sheets discharged via the discharge means; and an arm member configured to press the bundles of sheets stacked on the saddle tray in a direction of a stacking surface of the saddle tray, wherein the saddle tray and the arm member are coupled to the movable tray.
 3. The sheet post-processing apparatus according to claim 1, wherein: the saddle tray includes a sheet stacking unit configured to stack the bundles of sheets and a stopper configured to prevent the bundles of sheets stacked on the sheet stacking unit from falling off; and the stopper is formed to stand on the sheet stacking unit at a tip end portion on a downstream end in a transportation direction of the bundles of sheets.
 4. The sheet post-processing apparatus according to claim 2, wherein: the saddle tray includes a sheet stacking unit configured to stack the bundles of sheets and a stopper configured to prevent the bundles of sheets stacked on the sheet stacking unit from falling off; and the stopper is formed to stand on the sheet stacking unit at a tip end portion on a downstream end in a transportation direction of the bundles of sheets.
 5. The sheet post-processing apparatus according to claim 2, wherein: the arm member has an oscillation supporting point between the movable tray and the saddle tray and is configured to be able to oscillate in response to a height of the bundles of sheets stacked on the saddle tray.
 6. The sheet post-processing apparatus according to claim 2, wherein: the arm member includes a guide member on the paper discharge means side that is configured to guide the bundles of sheets in the direction of the stacking surface of the saddle tray; and the guiding member is configured to oscillate upon contact with the bundles of sheets discharged from the paper discharge means so as to be capable of absorbing a force in the transportation direction of the bundles of sheets.
 7. The sheet post-processing apparatus according to claim 2, wherein: the arm member includes a rotatable guide roller at a tip end portion on a downstream end of a transportation direction of the bundles of sheets. 